1. Field of the Invention
The present general inventive concept relates to an electrophotographic toner and a method of preparing the same, and more particularly, to an electrophotographic toner which presents a reduced risk to human health and the environment and has excellent durability, and can be fixed at a low temperature and prepared in a fine particle size, and a method of preparing the electrophotographic toner whereby the toner is efficiently agglomerated.
2. Description of the Related Art
In electrophotographic processes and electrostatic recording processes, a developer used to visualize electrostatic images or electrostatic latent images can be classified into a two-component developer formed of toner and carrier particles and a one-component developer formed of only toner. The one-component developer can be classified into a magnetic one-component developer and a nonmagnetic one-component developer. Fluiding agents such as colloidal silica are often independently added to the nonmagnetic one-component developer in order to improve fluidity of toner. Generally, coloring particles prepared by dispersing a pigment such as carbon black or other additives in a latex are used as toner.
Toner can be prepared by pulverization or polymerization. According to the pulverization method, toner is prepared by melting and mixing synthetic resins with pigments and, if required, other additives, pulverizing the mixture, and sorting particles until particles of a desired size are obtained. According to the polymerization method, a polymerizable monomer composition is manufactured by uniformly dissolving or dispersing various additives such as a pigment, a polymerization initiator and, if required, a cross-linking agent and an antistatic agent in a polymerizable monomer. Then, the polymerizable monomer composition is dispersed in an aqueous dispersive medium which includes a dispersion stabilizer using an agitator to shape minute liquid droplet particles. Subsequently, a temperature is increased and suspension polymerization is performed to obtain polymerized toner having coloring polymer particles of a desired size.
In image forming apparatuses such as electrophotographic apparatuses or electrostatic recording apparatuses, an image is formed by exposing an image on a uniformly charged photoreceptor to form an electrostatic latent image; attaching toner to the electrostatic latent image to form a toner image; transferring the toner image onto a transfer member such as transfer paper or the like; and then fixing the toner image on the transfer member using any of a variety of methods including heating, pressurizing, solvent seaming, and the like. In most fixing processes, the transfer medium with the toner image passes through fixing rollers and pressing rollers, and by heating and pressing, the toner image is fused to the transfer medium.
Images formed by an image forming apparatus such as an electrophotocopier should satisfy requirements of high precision and accuracy. Conventionally, toner used in an image forming apparatus is usually obtained using pulverization. In pulverization, coloring particles having a large range of sizes are formed. Thus, to obtain satisfactory developing properties, there is a need to sort the coloring particles obtained through pulverization according to a size to reduce the particle size distribution. However, precisely controlling the particle size and the particle size distribution using a conventional mixing/pulverizing process in the manufacture of toner suitable for an electrophotographic process or an electrostatic recording process is difficult. Also, when preparing a fine-particle toner, the toner preparation yield is adversely affected by the sorting process. In addition, there are limits to change/adjustment of a toner design for obtaining desirable charging and fixing properties. Accordingly, polymerized toner, the size of particles of which is easy to control and which do not need to undergo a complex manufacturing process such as sorting, has been highlighted recently.
When toner is prepared through polymerization, polymerized toner having a desired particle size and particle size distribution can be obtained without pulverizing or sorting. However, although such polymerization is used, agglomeration of a latex and a coloring agent is not efficiently performed, and an aluminum-based material used as an agglomerating agent is hazardous to human health and the environment.